Known in the art are various apparatus known as magnetic filters or magnetic separators which are employed as fine filters to remove ferromagnetic particles from fluids.
Known is an apparatus (cf. USSR Inventor'Certificate No. 698,658, published on Nov. 25, 1979) incorporating a cylindrical housing comprising two chambers one of which, filled with a ferromagnetic filtering packing, is contained in a means of magnetization in the form of a solenoid. A negative side of the known apparatus is a significant demand for the winding wire of the magnetization system, for each turn of the solenoid is of a diameter equalling at least the outside diameter of the housing.
Known is another apparatus (cf. USSR Inventor's Certificate No. 784,894 of Dec. 7, 1980) comprising at least five or even six chambers rigidly attached to a common base plate in an imaginary circle. Interposed between the chambers packed with a ferromagnetic filtering material, there are electromagnets having straight cores contacting plates in a soft magnetic material which are attached to the chamber walls. The electromagnets alternate with the packed chambers, forming a closed circular magnetic circuit.
The disadvantage of this apparatus is poor maneuverability. Firstly, the existing plurality of chambers renders it suitable mainly for handling high flow rates; no disconnection of separate chambers can offer an economic gain because of the magnetic circuit being common for all the chambers. Consequently, no power saving can be obtained in this case. The fact that the magnetic circuit is common for all the chambers renders regeneration of the packing in some of the chambers impossible while the apparatus is in operation. Thus, unproductive down periods associated with the regeneration of the packing are unavoidable, making continuous filtration impossible. Secondly, the known apparatus is not fit for operation in explosive surroundings, e.g. in an ammonia plant, because of the winding. The use of explosion-proof permanent magnets, arranged to interrupt periodically the magnetic flux to which the packing is exposed, invites difficulties.